Oral N-acetylcysteine decreases IFN-γ production and ameliorates ischemia-reperfusion injury in steatotic livers.

Type 1 Natural Killer T-cells (NKT1 cells) play a critical role in mediating hepatic ischemia-reperfusion injury (IRI). Although hepatic steatosis is a major risk factor for preservation type injury, how NKT cells impact this is understudied. Given NKT1 cell activation by phospholipid ligands recognized presented by CD1d, we hypothesized that NKT1 cells are key modulators of hepatic IRI because of the increased frequency of activating ligands in the setting of hepatic steatosis. We first demonstrate that IRI is exacerbated by a high-fat diet (HFD) in experimental murine models of warm partial ischemia. This is evident in the evaluation of ALT levels and Phasor-Fluorescence Lifetime (Phasor-FLIM) Imaging for glycolytic stress. Polychromatic flow cytometry identified pronounced increases in CD45+CD3+NK1.1+NKT1 cells in HFD fed mice when compared to mice fed a normal diet (ND). This observation is further extended to IRI, measuring ex vivo cytokine expression in the HFD and ND. Much higher interferon-gamma (IFN-γ) expression is noted in the HFD mice after IRI. We further tested our hypothesis by performing a lipidomic analysis of hepatic tissue and compared this to Phasor-FLIM imaging using "long lifetime species", a byproduct of lipid oxidation. There are higher levels of triacylglycerols and phospholipids in HFD mice. Since N-acetylcysteine (NAC) is able to limit hepatic steatosis, we tested how oral NAC supplementation in HFD mice impacted IRI. Interestingly, oral NAC supplementation in HFD mice results in improved hepatic enhancement using contrast-enhanced magnetic resonance imaging (MRI) compared to HFD control mice and normalization of glycolysis demonstrated by Phasor-FLIM imaging. This correlated with improved biochemical serum levels and a decrease in IFN-γ expression at a tissue level and from CD45+CD3+CD1d+ cells. Lipidomic evaluation of tissue in the HFD+NAC mice demonstrated a drastic decrease in triacylglycerol, suggesting downregulation of the PPAR-γ pathway.

The parallel paradigm between intestinal transplant inflammation and inflammatory bowel disease.

PURPOSE OF REVIEW: A significant shift in our understanding of the molecular and cellular basis for inflammatory bowel disease (IBD) mirrors research that has been ongoing in intestinal transplantation. The blurring of lines between these two disease states creates an avenue into potential therapeutic interventions which take advantage of these molecular similarities. RECENT FINDINGS: Traditional knowledge of T-cell involvement in IBD has expanded to highlight the role of T helper 17 (Th17) cells as key effector cells. A similar role has been demonstrated in cellular rejection of intestinal allografts. Genetic polymorphism related to the propagation and function of Th17 cells has been found to confer significant risk of developing autoimmune conditions. Interleukin-23, a cytokine identified as crucial to the expansion of Th17 cells, has become a validated molecular target in psoriatic arthritis and IBD, and could become a target for intestinal transplant therapies. SUMMARY: Intestinal transplant rejection and IBD share a similar phenotype, especially as it relates to key effector cells and gene polymorphisms. Improvements in our understanding of the immune-pathogenesis of IBD, as well as molecular targeting exploiting that knowledge, provide a potential route to improve outcomes for intestinal transplant patients.

Early treatment with fumagillin, an inhibitor of methionine aminopeptidase-2, prevents Pulmonary Hypertension in monocrotaline-injured rats.

Pulmonary Hypertension (PH) is a pathophysiologic condition characterized by hypoxemia and right ventricular strain. Proliferation of fibroblasts, smooth muscle cells, and endothelial cells is central to the pathology of PH in animal models and in humans. Methionine aminopeptidase-2 (MetAP2) regulates proliferation in a variety of cell types including endothelial cells, smooth muscle cells, and fibroblasts. MetAP2 is inhibited irreversibly by the angiogenesis inhibitor fumagillin. We have previously found that inhibition of MetAP2 with fumagillin in bleomycin-injured mice decreased pulmonary fibrosis by selectively decreasing the proliferation of lung myofibroblasts. In this study, we investigated the role of fumagillin as a potential therapy in experimental PH. In vivo, treatment of rats with fumagillin early after monocrotaline injury prevented PH and right ventricular remodeling by decreasing the thickness of the medial layer of the pulmonary arteries. Treatment with fumagillin beginning two weeks after monocrotaline injury did not prevent PH but was associated with decreased right ventricular mass and decreased cardiomyocyte hypertrophy, suggesting a direct effect of fumagillin on right ventricular remodeling. Incubation of rat pulmonary artery smooth muscle cells (RPASMC) with fumagillin and MetAP2-targeting siRNA inhibited proliferation of RPASMC in vitro. Platelet-derived growth factor, a growth factor that is important in the pathogenesis of PH and stimulates proliferation of fibroblasts and smooth muscle cells, strongly increased expression of MetP2. By immunohistochemistry, we found that MetAP2 was expressed in the lesions of human pulmonary arterial hypertension. We propose that fumagillin may be an effective adjunctive therapy for treating PH in patients.

Restricted ketogenic diet enhances the therapeutic action of N-butyldeoxynojirimycin towards brain GM2 accumulation in adult Sandhoff disease mice.

Sandhoff disease is an autosomal recessive, neurodegenerative disease involving the storage of brain ganglioside GM2 and asialo-GM2. Previous studies showed that caloric restriction, which augments longevity, and N-butyldeoxynojirimycin (NB-DNJ, Miglustat), an imino sugar that hinders the glucosyltransferase catalyzing the first step in glycosphingolipid biosynthesis, both increase longevity and improve motor behavior in the beta-hexosaminidase (Hexb) knockout (-/-) murine model of Sandhoff disease. In this study, we used a restricted ketogenic diet (KD-R) and NB-DNJ to combat ganglioside accumulation. Adult Hexb-/- mice were placed into one of the following groups: (i) a standard diet (SD), (ii) a SD with NB-DNJ (SD + NB-DNJ), (iii) a KD-R, and (iv) a KD-R with NB-DNJ (KD-R + NB-DNJ). Forebrain GM2 content (mug sialic acid/100 mg dry wt) in the four groups was 375 +/- 15, 312 +/- 8, 340 +/- 28, and 279 +/- 26, respectively, indicating an additive interaction between NB-DNJ and the KD-R. Most interestingly, brain NB-DNJ content was 3.5-fold greater in the KD-R + NB-DNJ mice than in the SD + NB-DNJ mice. These data suggest that the KD-R and NB-DNJ may be a potential combinatorial therapy for Sandhoff disease by enhancing NB-DNJ delivery to the brain and may allow lower dosing to achieve the same degree of efficacy as high dose monotherapy.